Omicron-[2-halo-1-(polyhalophenyl) vinyl] esters of omicron, omicron-dialkyl phosphorothioic and omicron-alkyl alkylphosphonothioic acids as insecticides



United States Patent No. assess 8 Claims. {CL 167-450) This applicationis a division of Serial No. 253,981, filed January 25, 1963 and issuedas US. 3,174,990 on March 23, 1965.

This invention relates to a new class of phosphoruscontaining esterswhich have been found to be particularly useful as insecticides. Membersof this class have shown high activity toward a wide spectrum ofinsects, with particularly high activity with respect to flies,mosquitoes, caterpillars, worms and beetles. Further, members of thisclass have been found effective in soil, and also have been found tohave a moderately long life, both in soil and on the surface of plantsexposed to light and air-because of which the compounds are ofparticular value as insecticides for applications in which it is desiredto protect plants from insects for a substantial period of timef0rexample, during growing and/or blooming stages yet it is not desirableto have carryover of the insecticide-for example, into the harvest stageand/or into the following season. Still further, compounds of thisinvention have been found to have relatively low mammalian toxicity,with some members having outstandingly low mammalian toxicity-so thatthese compounds are relatively safe to use.

The compounds of this invention can be described by the formula:

wherein alkyl represents an alkyl radical of from 1 to 4 carbon atoms, nis O or 1, X is bromine or chlorine and X is hydrogen, bromine orchlorine.

Referring to the halogen atoms bonded to the phenyl ring, they all maybe the same, or they may be different, and they may be bonded at anycombination of positions on the ring.

Compounds of this class wherein each alkyl radical is methyl or ethyl,and at least one of the halogen atoms is bonded to the carbon atom inthe ortho position of the phenyl ring, relative to the bond joining thering to the indicated carbon atom of the vinyl structure, appear to havethe highest insecticidal activity.

To illustrate and demonstrate the character of the compounds of thisinvention, and their nomenclature, the following species thereof are setforth:

0,0 dimethyl 0-(2chloro-l-(2,4-dichlorophenyl)vinyl) phosphorothioate;

0,0 diethyl 0 (2-chloro-1-(2,4-dichlorophenyl)vinyl) phosphorothioate;

0,0 dimethyl O-(2-bromo-1-(2,4-dichlorophenyl)vinyl) phosphorothioate;

0,0 dimethyl O-(2-chloro-1-(2,4-dibromophenyl)vinyl) phosphorothioate;

0,0 dimethyl O-(2-bromo-1-(2,4-dibromophenyl)vinyl) phosphorothioate;

0,0 dimethyl O-(2-chloro-1-(2,5-dichlorophenyl)vinyl) phosphorothioate;

3,242,043 Patented Mar. 22, 1966 0,0 diethylO-(Z-chloro-1-(2,5-dichlorophenyl)vinyl) phosphorothioate;

0,0 dimethyl 0-(2-bromo-1-(2,5-dichlorophenyl)vinyl) phosphorothioate;

0,0 dimethyl 0-(2-bromo-1-(2,4-dibromophenyl)vinyl) phosphorothioate;

0,0 diethyl O (2-chloro-l-(2,4-dibromophenyl)vinyl) phosphorothioate;

O ethyl O-(2-chloro1-(2,4-dichl'orophenyl)vinyl) methylphosphonothioate;

O ethyl 0-(2-bromo-1-(2,4-dichlorophenyl)vinyl) methylphosphonothioate;

O-ethyl 0-(2-bromo-1-(2,4-dibromophenyl)vinyl) methylphosphonothioate;

O ethyl O-(2-chloro-1-(2,4-dibromophenyl)vinyl) methylphosphonothioate;

O ethyl 0-(2-chloro-l-(2,4-dichlorophenyl)vinyl) ethylphosphonothioate;

O methyl 0 (Z-chloro-1-(2,4-dichloropheny1)vinyl)methylphosphonothioate;

0,0 dimethyl 0 (2,2-dichloro-1-(2,4-dich1orophenyl) vinyl)phosphorothioate;

0,0 diethyl O (2,2-dichloro-1-(2,4 dichlorophenyl) vinyl)phosphorothioate;

0,0-dimethyl 0-2,2-dibromo-1 (2,4-dichlorophenyl vinyl)phosphorothioate;

0,0 dimethyl O (2,2-dichloro-1-(2,5-dichlorophenyl) vinyl)phosphorothioate;

0,0 dimethyl O (2,2-dibromo-l-(2A-dibrornophenyl) vinyl)phosphorothioate;

0,0 dimethyl 0 (2,2-dibromo-1-(2,5-dibromophenyl) vinyl)phosphorothioate;

0,0 dimethyl O (2,2-dichloro-1-(2,4-dibromophenyl) vinyl)phosphorothioate;

O ethyl 0 (2,2-dichloro-1-(2,4-dichlorophenyl)vinyl)methylphosphonothioate;

0 methyl 0-(2,2-dichloro-l-(2,4-dichlorophenyl)vinyl)methylphosphonothioate;

0 ethyl 0 (2,2-dichloro-1-(2,4-dichlorophenyl)vinyl)ethylphosphonothioate;

O ethyl 0 (2,2-dibromo-l-(2,4-dichlorophenyl)vinyl)methylphosphonothioate;

0 ethyl O (2,2-dichloro-l-(2,4-dibromophenyl)vinyl)methylphosphonothioate;

0 ethyl O (2,2-dibromo-1-(2,4-dibromophenyl)vinyl)methylphosphonothioate;

0 ethyl 0 (2,2-dichloro-1-(2,5-dichlorophenyl)vinyl)methylphosphonothioate;

0,0 diethyl 0 (1-(2-bromo-4-ch1orophenyl)2chlorovinyl) phosphorothioate;

0,0 dimethyl O-(1-(2-bromo-5-chlorophenyl)2-chlorovinyl)phosphorothioate;

0,0 dimethyl O-(1-(2-bromo-4-chlorophenyl)2-chlorovinyl)phosphorothioate;

0,0 dimethyl 0 (1 (2 bromo-4-chlorophenyl)2,2-

dichlorovinyl) phosphorothioate.

The compounds of the invention can be prepared by reaction of anappropriate alpha-haloacetophenone with an appropriate phosphoroorphosphonohalidothionate in the presence of a base, according to thegeneral equation:

alkyl-O S P-halogen base alkyl 0 wherein the symbols have the respectivemeanings already set out herein.

The reaction is conveniently carried out by mixing about equimolaramounts of the reactants and base together, in a suitable solvent, at atemperature above about C. The reaction has been conducted at about roomtemperature or slightly above (up to about 35 C.) using ether assolvent. Other solvents, such as benzene, can be used, and highertemperatures can be used. A convenient and effective technique is to addthe ketone, in the solvent, to a mixture of the base and the phosphoroorphosphonochloridothionate in the solvent, with thorough mixing. Sodiumhydride is a suitable base.

The alpha-polyhaloacetophenones can be prepared by halogenating theappropriate acetophenones. Alternatively, thealpha-polyhaloacetophenones can be prepared by an orthodoxFriedel-Crafts ketone synthesis (described generally in Fieser andFieser, Organic Chemistry, second edition, 1950, at pages 576-7), byreacting the appropriate polyhalobenzene with the appropriatepolyhaloacetyl chloride in the presence of aluminum chloride, thendecomposing the resulting complex with ice and hydrochloric acid.

The polyhalobenzenes are a well-known class of compounds (LangesHandbook), as are the polyhaloacetyl chlorides (Huntress, OrganicChlorine Compounds, Wiley 1948).

The reaction is carried out as described in Fieser and Fieser-that is,the aluminum chloride is mixed with the polyhalobenzene, then theresulting mixture is mixed with the polyhaloacetyl chloride, ordinarilyat room temperature, the mixture is allowed to heat, or is heated toabout 80-100 C., maintained at that temperature for a sufiicient time tocomplete the formation of the complex, then the mixture is cooled andtreated with an ice-hydrochloric acid mixture to decompose the complexand separate out water-soluble aluminum salts. About one mole of theacetyl chloride is used per mole of the polyhalobenzene, and ordinarilyit will be found advantageous to use about a 10% excess of aluminumchloride, or about 1.1 mole per mole of the polyhalobenzene. Where thepolyhalobenzene is liquid at room temperature, usually no added solventwill be required. Where the polyhalobenzene is solid at roomtemperature, or it is desired to maintain a more fluid mixture than canbe obtained with the liquid polyhalobenzene alone, a solvent may beadded, suitable solvents including carbon disulfide, nitrobenzene,nitromethane, and the like.

The ketone product ordinarily is most effectively and convenientlyrecovered by treating the mixture obtained on decomposition of thecomplex with a suitable selective solvent, ether being suitable,separating the organic phase from the aqueous phase, stripping thesolvent from the organic phase, then distilling the residue to give theketone product.

The product suitably is recovered by filtering the final crude reactionmixture, removing the solvent, then crystallizing the product from asuitable solvent, such as pentane.

The manner in which compounds of this invention are thus prepared isillustrated in the following examples, which detail preparation oftypical species of these compounds. In these examples, parts means partsby weight unless otherwise indicated, with parts by weight bearing thesame relationship to parts by volume as does the kilogram to the liter.

EXAMPLE I (A) Preparation 0 0,0-diethyl O-(2-chl0r0-1-(2,4-dichl0r0phenyl)vinyl) phosphorothioate 7.2 parts of sodium hydride as a50% dispersion in mineral oil was mixed with 200 parts by volume ofether, and the mixture mixed, slowly over a period of one hour, with 67parts of 2,2,4'-trichloroacetophenone in 500 parts by volume of ether.The mixture was stirred for an additional one hour, then 68 parts ofdiethyl phosphorochloridothionate was added to the stirred mixture overa period of one hour. The mixture was stirred for an additional 3 hours.An additional 14 parts of the thionate was then added and the mixturestirred for an additional 16 hours. An additional 14 parts of thethionate then was added and the mixture was stirred for another 6 hours.The mixture then was poured into 200 parts by volume of water, the etherphase was separated, washed with water, and dried. The ether then wasstripped and the residue was distilled. On standing the distillatecrystallized. Recrystallized product had a melting point of 48.549.5 C.The produce was identified as 0,0-diethylO-(2-chloro-1-(2,4-dichlorophenyl)vinyl) phosphorothioate by ele mentalanalysis.

Elemental analysis (percent by weight).-Calculated: percent P-8.25;percent S8.5; percent Cl28.4. Found: percent P8.27; percent S8.4;percent Cl29.0. The identity was confirmed by infra-red spectrumanalysis.

(B) In a similar manner there was prepared 0,0-dimethylO-(2-chloro-1-(2,4-dichlorophenyl)vinyl) phosphorothioate, melting point48.549.5 C.

EXAMPLE II (A) Preparation of 0,0-diethyl O-(2-chlor0-1-(2,5-dichlorophenyl) vinyl) phosphorothioate 4.95 parts of sodium hydride asa 50% dispersion in mineral oil was mixed with parts by volume of etherand over a 15 minute period 46.6 parts of diethylphosphorochloridothionate was added. This mixture was mixed, over a 5.5hour period, with a mixture of 46 grams of 2,2,5'-trichloroacetophenonein 200 parts by volume of ether, the temperature being held at 28-34 C.The resulting mixture then was heated to reflux and refluxed for 1.5hours. The mixture then was filtered and the ether stripped. The residuewas extracted with pentane and 0,0-diethylO-(2chloro-(2,5-dichlorophenyl)vinyl) phosphorothioate was recovered bycrystallization. Melting point: 27.528.5 C. The identity of the productwas established by elemental analysis and confirmed by infrared spectrumanalysis.

(B) In a similar manner there was prepared 0,0-dimethylO-(2-chloro-l-(2,5'dichlorophenyl)vinyl) phosphorothioate, melting point81-82 C.

EXAMPLE III In essentially the same manner as described in the foregoingexamples, the following additional species of the compounds of thisinvention were prepared:

(A) 0,0-dimethyl O-(2-chloro-1-(2,4-dibromophenyl) vinyl)phosphorothioate, melting point: 5556 C.;

(B) 0,0-diethyl O-(Z-chloro-l-(2,4-dibromophenyl)vinyl)phosphorothioate; melting point: 66-67 C.;

(C) 0,0-dimethyl O-(2-chloro-l-(2,5-dibromophenyl) vinylphosphorothioate, melting point: 89-90.5 C.;

(D) 0,0-dimethyl O-(Z-chloro-l-(2-bromo-4-chlorophenyl)vinylphosphorothioate, melting point: 4950 C.;

(E) 0,0 diethyl O (2-chloro-1=(2-bromo-4-chlorophenyl)vinyl)phosphorothioate, melting point: 54- 56 C.;

(F) Oet-hyl O-(2chloro-1-(2,4-dichlorophenyl)vinyl)methyl-phosphonothioate, boiling point: C. at 0.005 Torr.;

(G) 0,0-cliethyl O-(2,2-dichloro-1-(2,4-dichlorophenyl)vinyl)phosphorothioate, boiling point: 125 C. at 0.005 Torr.;

(H) 0,0 dimethyl O (2,2-dichloro-1-(2,4-dichlorophenyl)vinyl)phosphorothioate, melting point: 345 C.

Compounds of this invention have been found to be effectiveinsecticides, against a variety of insects typical of various kinds ofinsects, including flies, mosquitoes, worms, caterpillars, weevils andbeetles. These compounds are stable on storage, are essentiallynonphytotoxic at insecticidally efiective dosages, are efiective in soiland are particularly effective against dipterous insects (flies),

coleopterous insects (beetles), caterpillars and mosquitoes.

By the term insects" thus is meant not only the members of the classInsecta, but also similar invertebrate animal organisms belonging to theallied classes of arthropods and including ticks, mites, spiders, andthe like.

. Compounds of this invention are effective against the immature formsof insects as well as against the mature forms which attack plants.Thus, these compounds kill worms, by which is meant not only the trueworms, but also those immature forms of insectslarvae, etc.-which aregenerally known as worms, and including larvae of the western spottedcucumber beetle (Diabrotica undecimpunctata undecz'mpunctwta), cornearworms (Heliothis 6 earwor'r'n larvae on cut broad bean plantsinserted in water after formulations of the test compounds, prepared bydissolving acetone solutions of the compounds in water, had been sprayedthereon. Two replicates were used with each test, various tests beingdirected to different concentrations of the test compounds in the liquidformulations. The LC values are set out on Table I. In a similar manner,tests were conducted with respect .to eaterpillars of the diamondbackmoth (Plutella maculipennis), the imported cabbage worm (Pieris mpae)and larvae of the elm leaf beetle (Galerucella luteola), with theresults (LC being set out in Table I. The activity of compounds of theinvention with respect to the rice weevil (Sz'tophilus oryzae), wasdetermined by pouring a Zea), imported cabbage worms (Pier-is rapae),Pacific 5 measured amount of a solution of the test compound Coastwireworm (Limonius canus) and the like. over adult rice weevils in acontainer having a perforated The efiectivene sof compounds of thisinvention a in bottom, excess solution immediately draining away. Tensecticides is demonstrated by the following experiments seconds afterthe solution had been poured on the weevils, and the results thereof. Ithe weevils were dried with blotter paper, transferred to In theinterest of brevity, in the following examples, go containers and heldin a controlled temperature and the species of the compounds of theinvention will be rehIImIdItYTOOIII O 24 u s a then ade to ferred byletter, as follows: determine the number of weevils killed (whichincludes Table-1 LCao (percent) for Test Insect Test Compound House-Vinegar Corn Rice Diamond- Imported Elm fly fly Earworm Weevil back mothCabbage Leaf worm Beetle Compound A" 0.0057 0.00113 0. 0027 0 00183Compound B Compound C Compound D Compound E Compound F Compound (3.-Compound I-L. Compound I Compound J. Compound 1L. Compound L*Mierograms.

Compound: Compound of example A IA B IB C IIA D IIB E IIIA F IIIB G IIICH IIID I IIIE J IIIF K IIIG L IIIH EXAMPLE IV Solutions of certain ofthe novel compounds of the invention were made up employing either aneutral petroleum distillate boiling within the kerosene range oracetone as the solvent. Tests were carried out using the common housefly(Musca domestica), as the test insect, the method used being thatdescribed by Y. P. Sun, Journal of Economic Entomology, volume 43, pp.45, et seq. (1950). Table I shows the concentration (in percent) oftoxic agent in the sprayed solution required to cause 50 percentmortality of the test insecti.e., the LC concentration. Similar testswere conducted using the vinegar fly (Drosophila melanogaster) as thetest insect. The results (LC are reported in Table I. The activity ofcompounds of the invention with respect to the corn earworm (HeliothisZea), was determined by caging corn moribund weevils), Severalreplicates are conducted, several concentrations of the test compound inthe solution being used. Table I sets out the LC concentrations ofcompounds of the invention with respect to these weevils.

EXAMPLE V Activity of compounds of the invention with respect to theboll weevil (Anthonomus grandis) was established as r follows: bollweevils were caged at intervals after treatment (at the rate of 0.5pound of active material per acre) on cotton plants in the field. Threeto five cages, each containing 10 weevils are placed on terminalbranches of treated plants. Mortality counts were made 2448 hours afterinfestation. It was found that Compound B gave 96 percent control, undersuch conditions.

EXAMPLE VI Compounds of the invention also were tested to determinetheir toxicity with respect to mosquito (Anopheles albimanus) larvae asfollows: sufficient of a 1% acetone solution of the test compound wasdissolved in 100 milliliters of water to provide the desiredconcentration of the compound. Ten fourth-instar A. albimanus larvaewere introduced into each of two replicates. The larvae were exposed tothe solution of the test compound for twenty-four hours, then mortalitycounts were made. Various concentrations of the test compounds were usedto determine the LC concentration, expressed in parts by Weight of testcompound per million parts by weight of the solution. Table IIsummarizes the results.

7 Table II Test compound: LC

B 0.0016 C 0.008 D 0.008

I 0.0095 K 0.0049 L 0.0115

EXAMPLE VII The residual properties of compounds of the invention weredetermined as follows: solutions of the test compounds in acetone weresprayed upon the surface of plywood panels and test insects cagedagainst the treated panels, one series of exposures being madeimmediately after application of the test material, and later series ofexposures being made at weekly intervals thereafter. The test insectswere adult common houseflies (Musca domestica) and Anopheles albimanusmosquitoes. At a dosage of 50 milligrams of the test material per squarefoot of the surface of the wood, the following control of houseflies andmosquitoes was obtained:

Compound A: 91 percent control of houseflies at the end of 4 weeks; 100%control of mosquitoes at the end of 8 weeks;

Compound B: 100 percent control of both houseflies and mosquitoes at theend of 8 weeks;

Compound C: 94 percent control of houseflies end of 8 weeks and 100%control of mosquitoes end of 8 weeks;

Compound D: 62 percent control of houseflies end of 8 weeks and 100%control of mosquitoes end of -8 weeks;

Compound E: 97 percent control of houseflies end of 4 weeks and 100%control of mosquitoes end of 8 weeks;

Compound F: 93 percent control of houseflies end of 4 weeks and 100%control of mosquitoes end of 8 weeks;

Compound H: 100 percent control of houseflies at the end of 2 weeks,with 63% control at the end of 8 weeks, and 100% control of mosquitoesat the end of 4 weeks;

Compound I: 98 percent control of houseflies at the end of 2 weeks, and100% control of mosquitoes at the end of 4 weeks.

at the at the at the at the at the at the at the at the EXAMPLE VIII Theeffectiveness and substantial life of insecticides of this invention insoil was demonstrated by the following tests:

An acetone solution of the test compound was sprayed onto soil, as thesoil was being tumbled in a mixer, so as to uniformly disseminate thetest compound into the soil and provide a concentration of 3.3 parts byweight of the test material per million parts by weight of the soil. Thesoil then was dried to remove the acetone, moistened with water anddivided into jars. The jars were sealed and held at 80 F. One day afterthe soil had been placed in the jars, certain of the jars were openedand fourth instar larvae of the western spotted cucumber beetle(Diabrotica wzdecimpunctata undecimpunctata) were introduced into thesoil. The jars were sealed, held for 24 hours, then the mortality of thelarvae was determined. This procedure was repeated at intervals of 8,15, 22, 29, 36 and 43 days after introduction of the treated soil intothe jars.

8 The following results were obtained:

Table III Percent control, i at indicated day after introduction of testcompound into the Test Compound soil Compound A 1 100 100 100 100Compound B 100 100 100 Compound C 100 100 100 Compound 1).... 100 100100 Compound El." 100 100 100 Compound F 100 90 Compound H. 100 100 90Compound I 100 100 100 90 Compound I t. 100 100 100 Compound L 100 90 60t.

1 At a dosage of 2 parts per million.

2 90% control at the end of 10 weeks.

EXAMPLE IX During the conduct of these insecticidal tests, there wasobserved no phytotoxiclty by the insecticides at the concentrationsused.

The compounds of this invention can be employed for insecticidalpurposes by the use of any of the techniques which are conventionallyemployed in the art, with due regard to the particular applicationcontemplated-i.e., whether the compound is to be applied to the surfacesof plants, buildings and the like, and including the surface of soil,and absorptive materials such as paper, sand, bricks, concrete, plaster,plant materials used in buildings, and the like, whether it is to bedisseminated into soil, whether it is to be incorporated into surfacecoatings, such as waxes, resins, paints, lacquers, varnishes, whether itis to be incorporated in various plastic materials, including plasticsheetings, in order to obtain packaging and wrapping materialsthemselves resistant to insect attack and able to protect objects packedin them from such attack, or whether it be used in some other mannersuch as to exploit the long life of compounds of the invention.

When a compound of this invention is to be used as a conventionalinsecticide applied to surfacesof plants,

buildings, soil and other absorptive materials or the like the compoundcan either be sprayed or otherwise applied in the form of a solution ofdispersion, or it can be absorbed on an inert, finely divided solid andapplied as a dust. Useful solutions for application by spraying,brushing, dipping, and the like can be prepared by using as the solventany of the well-known inert horticultural carriers, including neutralhydrocarbons such as kerosene and other light mineral oil distillates ofintermediate viscosity and volatility. Adjuvants, such as spreading orwetting agents, can also be included in the solutions, representativematerials of this character being fatty acid soaps, rosin salts,saponins, gelatin, casein, long-chain fatty alcohols, alkyl arylsulfonates, long-chain alkyl sulfonates, phenolethylene oxidecondensates, C to C amines and ammonium salts, and the like. Thesesolutions can be employed as such, or more preferably they can bedispersed or emulsified in water and the resulting aqueous dispersion oremulsion applied as a spray. Solid carrier materials which can beemployed include talc, bentonite, lime, gypsum, pyrophyllite and similarinert solid diluents. If desired, the compound of the present inventioncan be employed as an aerosol, as by dispersing the same into theatmosphere by means of a compressed gas.

The concentration of the compound to be used with the above carriers isdependent upon many factors, including the particular compound utilized,the carrier employed, the method and conditions of application, and theinsecticide species to be controlled, a proper consideration andresolution of these factors being within the skill of those versed inthe insecticide art. In general, however,

the compounds of this invention are effective in concentrations of fromabout 0.01 to 0.5% based upon the total weight of the composition,though under some circumstances as little as about 0.0000l% or as muchas 2% or even more of the compound can be employed with good resultsfrom an insecticidal standpoint, as wherein high concentrations ofactive material are used in low-volume sprays or dusts.

Compounds of this invention are employed as soil insecticides byconventional techniques which insure uniform intimate disseminatioin ofan effective dosage of the compound in the soil. Judging by theexperimental work which has been performed, the insecticidally effectivedosages of compounds of the invention lie in the range of a few partsper million parts by weight of the soil. Thus, the effective dosagesappear to lie within the range of from about three to five parts, up toabout fifty to one hundred parts per million, on a weight basis based onthe Weight of the air-dry soil. This is not to say that in some cases, ahigher dosage-of up to as much as 500 parts per million on the samebasismay not be used to advantage, but in most cases the effectivedosage appears to lie within the range of from about 3 to about 50 partsper million on that basis. In more practical terms, the effective dosageappears to amount to from about 0.25 to about 100 pounds of theinsecticide per acre of land, depending upon the depth of soil to betreated, which may be as great as 3, 6 or 8, or even 12 inches,depending upon the particular species of plants and insects involved.Generally, dosages of from about 1 to about '10 pounds of theinsecticide per acre of land are preferred.

The insecticide may be dissolved and/ or dispersed in a suitable liquiddiluent and the solution or dispersion applied to and mixed with thesoil, or the insecticide may be formulated with a suitable solid carrierand applied as a dust, powder or as granules to the soil and admixedtherewith. The compounds of this invention are not very soluble inwater, so that Water is not a suitable solvent. By the use of suitableemulsifying and dispersing agents, however, these insecticides can beemulsified or dispersed in water and the emulsion applied to the soil tobe treated to provide effective control of the insects therein. Any ofthe usual emulsifying and dispersing agents commonly employed in formingaqueous emulsions and suspensions of water-insoluble materials can beused for this purpose. Generally but a small concentration of theemulsifying agent is required, as little as 0.05 percent of the weightof the final formulation being effective in many cases, while seldomwill more than about 10% of the Weight of the final formulation berequired. Usually, the concentration of the emulsifying or dispersingagent will be from about 0.5 to about percent of the weight of theformulation. Alternatively, or in addition, in some cases it may be toadvantage to dissolve the insecticide to be used in a solvent which canreadily be dispersed in water to produce a heterogeneous dispersion ofthe insecticide in the water.

Where the insecticide is to be applied as a solution, suitable solventsinclude water-miscible alcohols, ketones and aromatic hydrocarbons, suchas, for example, isopropyl alcohol, benzene, acetone, methyl ethylketone, secondary butyl alcohol, kerosene, chlorinated hydrocarbons,various nonphytotoxic hydrocarbon fractions which are ordinarily used indisseminating agricultural chemicals, including spray oils,horticultural oils, and the like.

The suitable solid carriers ordinarily are those which are essentiallyinert in the soil and which are not hygroscopicfor if they arehygroscopic the final formulation will not remain dry and free-flowing.In some cases, however, it may be desirable to employ as carrier a solidwhich is not inert-as, for example, a solid fertilizer such as acommerical mixed solid fertilizer, rock phosphate, urea or the like.Suitable inert carriers are those well known to the art including theclays such as the kaolinites, the

bentonites and the attapulgites; other minerals in natural state such astalc, pyrophyllite, quartz, diatomaceous earth, fullers earth, chalk,rock phosphate and sulfur; and chemically modified minerals, such asacid washed bentonites, precipitated calcium phosphates, precipitatedcalcium carbonate and colloidal silica. These diluents may represent asubstantial portion, for example, 50 to 98 percent by weight of theentire formulation.

These solid formulations can be prepared by grinding or air-milling thecarrier and insecticide together. Alternatively, the solid formulationscan be formed by dissolving the insecticide in a suitable solvent, such.as a volatile solvent, impregnating and/or coating the particles withthe solution and if necessary, removing the solvent. The formulationalso can be effected by melting the insecticide and mixing the molteninsecticide with the carrier. Granular formulations can be prepared byimpregnating and/ or coating granules of the carrier with theinsecticide or by forming granules of mixtures of the insecticide andcarrier.

From the standpoint of mechanics, the insecticide, neat or as aformulation, is applied to the soil in any manner which enables itsintimate admixture with the soil to be treated. Thus the insecticide,which includes formulations thereof, can be applied to the surface ofthe soil, or it can be applied below the surface of the soil, and thenadmixed with the soil. If in the form of a liquid formulation, theinsecticide can be drenched onto the surface of the soil or injectedinto the soil. In other words, conventional means, well known in theart, can be used to effect intimate admixture of the insecticide withthe soil to be treated.

The compounds of this invention are characterized by an extendedeffective life in the soil and essentially no phytotoxicity at theinsecticidally effective dosages. Consequently, it may not in all casesbe necessary to treat the entire mass of insect-infested soil-in somecases it may be suffiicent to treat only the soil of the rhizosphere ofthe plants to be protected. Thus, the soil immediately surrounding theroots of established trees can be treated to protect the trees, and rowcrops can be protected by treating only the soil which will surround theroots of the plants in each before the seeds or plants are planted, orafter the plants have been planted. The formulations of the insecticidecan also contain other materials, such as nematocides, fungicides,insecticides of different action and/or different physicalcharacteristics, hormones, and/or fertilizers, to form multipurposecompositions.

We claim as our invention:

1. A method for controlling insects which comprises subjecting insectsto an insecticidally effective amount of a phosphorus ester of theformula:

wherein alkyl represents alkyl of from 1 to 4 carbon atoms, n is aninteger from 0 to 1, X is a member of the group consisting of bromineand chlorine, and X is a member of the group consisting of hydrogen,bromine and chlorine.

2. A method for controlling insects which comprises subjecting insectsto an insecticidally effective amount of an ester of claim 1 whereinn-=l, X is hydrogen.

3. A method for controlling insects which comprises subjecting insectsto an insecticidally effective amount of 0.0-diethyl O (2 chloro 1(2,4dichlorophenyDvinyl) phosphorothioate.

4. A method for controlling insects which comprises subjecting insectsto an insecticidally effective amount of O-ethyl O- (2-chloro-1-(2,4-dichlorophenyl)vinyl) methylphosphonothiate.

5. An insecticidal composition containing (a) at least 0.01 percent byweight of the total composition of phosphorus ester of the formula:

alkyl-O S wherein alkyl represents alkyl of from 1 to 4 carbon atoms, nis an integer from 0 to 1, X is a member of the group consisting ofbromine and chlorine, and X is a member of the group consisting ofhydrogen, bromine and chlorine and (b) a suitable inert horticulturaladjuvant therefor.

6. An insecticidal composition containing at least 0.01 percent byWeight of the total composition of an ester of claim 1 wherein n=1, X ishydrogen and a suitable inert horticultural adjuvant therefor.

7. An insecticidal composition containing at least 0.01 percent bywegiht of the total composition of 0,0'-diethylO-(Z-chloro-1-(2,4-dichloropheny1)vinyl) phosphorothioate and a suitableinert horticultural adjuvant therefor.

8. An insecticidal composition containing at least 0.01 percent byWeight of the total composition of O-ethyl O- ('2- chloro 1(2,4-dichlorophenyl)vinyl) methylphosphonothioate and a suitable inerthorticultural adjuvant therefor.

References Cited by the Examiner UNITED STATES PATENTS 3,003,916 10/1961Gilbert ct al 16730 3,102,842 9/1963 Phillips et a1. 16730 3,116,20112/1963 Whetstone et a1 167-30 X 3,134,713 I 5/1964 Gilbert et al 16730JULIAN S. LEVITT, Primary Examiner.

1. A METHOD FOR CONTROLLING INSECTS WHICH COMPRISES SUBJECTING INSECTSTO AN INSECTICIDALLY EFFECTIVE AMOUNT OF A PHOSPHORUS ESTER OF THEFORMULA: